Casio Ctk 4400 won't power on

so about 6 month ago I bought this keyboard ctk 4400 It was going fine until one day I plugged the adapter to wall and keyboard and pressed the power button nothing happens..i tried many times Changing the wall outlet but the same problem everywhere nothing happens... Then i tried with batteries it works fine but not with the adapter... Can anyone plz tell me what might be the problem and also the solution ...